This invention relates to an improved hydraulically operated impact motor.
Most known hydraulically operated impact motors have hammer pistons which have two lands with a valve portion between the lands in order to obtain reliable valving functions. Such a prior system is shown in U.S. Pat. No. 3,780,621 in which two valve control lines are provided, both of which are alternately pressurized and relieved of pressure. One-land hammer pistons are known from U.S. Pat. No. 3,552,269 and British Pat. No. 1,436,079. Both of these prior one-land constructions are complicated and are thus not very reliable. The valve in U.S. Pat. No. 3,552,269 operates on restrictions which make it slow. In British Pat. No. 1,436,079 these are two valves which make the valving action slow.
The object of the present invention is to provide an improved and highly efficient hydraulic impact motor in which the construction is simple, and the valve is fast acting and very reliable.